1. Field of the Invention
This invention pertains to electric heating, and more particularly to variable capacity electric resistance heating.
2. Description of the Prior Art
It is a common practice to use electrical energy for heating purposes. A properly designed resistor placed in an electric circuit becomes heated upon energizing the circuit, and the resistor heats the surrounding environment.
Heating water is a common application of electric resistance heating. A resistor, often referred to as a heating element, is immersed in water stored in a vessel. Applying a voltage across the element terminals causes the temperature of the element to rise, thus heating the water. Heating elements having different ratings are often interchangeable within a water heater or other appliance. In that manner, water heaters having different capacities can be supplied merely by replacing a heating element of one rating with a heating element of another rating.
However, interchanging heating elements to obtain different capacity heaters has certain drawbacks. One drawback is that manufactures and dealers must make and stock different components corresponding to the different rating heating elements. It is well known, of course, that producing relatively few of several different parts and carrying those parts in inventory is undersirably expensive. In addition, changing heating elements requires care in handling the necessary tools and in assuring waterproof connections.
Thus, a need exists for improvements in electric heating elements.